The present invention relates to a body which is formed at least in regions in a hollow-cylindrical manner, is designated hereinafter as a hollow body, and has an integrated oil separating device. Preferably, the hollow body is formed by means of a camshaft.
International PCT publication WO 2006/119737 A1 discloses a hollow shaft having an integrated oil separating device, wherein in addition to a pre-separator, which is disposed on the outer periphery of the shaft, there is provided a swirl generator, which is integrated into the cavity of the shaft, as a final separator.
Furthermore, a camshaft having integrated oil separation is disclosed in a VDI-report “Nockenwelle mit integrieter Ölabscheideeinrichtung NÖA” [camshaft with an integrated oil separating device] (VDI-Reports no. 2042, 2008, page 152, Chapter 4 and FIG. 6), wherein a helical swirl generator is disposed in the cavity of the camshaft.
It is the object of the present invention to provide a generic hollow body having an integrated oil separating device which, even in the case of critical pressure ratios in the environment of the oil separating device, ensures a secure mode of operation thereof. In particular, a predetermined level of efficiency of the oil separation at different pressure ratios is to be ensured.
In accordance with the invention, this object is achieved by features claimed, with further expedient developments of the invention defined in the subordinate claims.
In accordance with the present invention, the swirl generator which is disposed in the interior of the hollow body comprises means for variably influencing the pressure prevailing in the cavity of the hollow body at a predetermined location. In an advantageous manner, these means are formed such that in the case of a pressure which occurs at the predetermined location and which is greater than or equal to a predetermined desired pressure, an automatic reduction of the actual pressure is effected at this location. In a first possible embodiment of the invention, the swirl generator which is integrated in the hollow body is of any design and is characterised by virtue of the fact that over its entire longitudinal extension it comprises an axial bypass channel, into which a pressure-dependent bypass valve is integrated. At least regions of the swirl generator are formed in such a manner that the swirl generator divides the cavity of the hollow body into two pressure regions which are separated or can be separated from each other in terms of pressure technology, wherein in the pressure region which is located downstream as seen in the flow direction, gas which is charged with oil can be introduced via the first supply opening into the cavity and gas which is likewise charged with oil can be supplied via a pressure region, which is located upstream as seen in the flow direction, via a second supply opening. The first supply opening as seen in the flow direction is disposed downstream of the pressure-separating part of the swirl generator and the second supply opening as seen in the flow direction is disposed upstream of the separating part of the swirl generator. In an advantageous manner, the bypass value which is integrated in the bypass channel is formed as a spring-loaded non-return valve such that when the predetermined pressure in the cavity of the hollow body is reached or exceeded the bypass valve opens and the bypass channel is released, so that the two pressure regions are connected together in terms of pressure and flow technology—they are connected together at least as long as the pressure in the cavity is greater than or equal to the predetermined pressure.
In a further embodiment, the means for variably influencing the pressure prevailing in the cavity are formed alternatively or additionally by virtue of the fact that the swirl generator is formed as a body which extends in the axial direction of the hollow body and which comprises on its periphery at least one screw channel. At least regions of the at least one screw channel are mounted in an axially displaceable manner on or at the basic body of the swirl generator—likewise in such a manner that when the predetermined pressure in the cavity of the hollow body is reached or exceeded the screw channel or screw channel portion is displaced in the flow direction in particular against a restoring force.
The invention will be described in greater detail hereinafter with the aid of various exemplified embodiments.